Airbag restraint systems are generally provided with some type of cover assembly which conceals the airbag system in an internal portion of a vehicle, e.g., in the passenger instrument panel, prior to the deployment of an airbag into the vehicle passenger compartment. Some airbag systems cover assemblies comprise a panel containing an integral deployment door, which is caused to open during the inflation of the hidden airbag, thereby providing a doorway outlet in the panel through which the inflating airbag deploys into the vehicle passenger compartment. The panel normally includes tear regions along the boundaries of the door which integrally joins the deployment door with the remaining areas of the panel. The panel in which the deployment door is contained is normally multilayered, comprising a decorative vinyl outer layer or "skin" separated by a foam core or "padding" from a metal or thermoplastic panel substrate.
In order to cause the deployment door to open, a tear means is generally aligned with the tear region which may include tear seams. The inflating force of the deploying airbag drives the tear means through the tear region to separate the deployment door from the rest of the panel. The deployment door is hinged along one side thereof or tethered to an interior vehicle substrate to prevent the release of the door into the passenger compartment to prevent injury to vehicle occupants.
Since the deploying airbag generates the force for opening the deployment door, the less force required in opening the deployment door, the better. Accordingly, a better definition of the tear region without creating a visible seam in the panel and/or limiting of fragmentation on opening the deployment door would enhance system performance.